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The redox properties and the reactivity of several areneruthenium(II) 4-acyl-5-pyrazolonate derivatives are described.

The following report outlines a simplified method to predict the effect on the relative growth rates of crystal facets resulting from different solvents. The method uses molecular dynamics (MD) techniques which are coupled to a Monte Carlo (MC) scheme to generate distributions of estimates of molecular binding energies at the crystal surface. We then use these calculated binding energies to make inferences on how solvent may affect the relative growth rate of the crystal facets (i.e., solvent effect on growth). We support the analysis by revisiting the growth of adipic acid. It is demonstrated that there is a remarkable increase in the sensitivity of the expected values used to represent the "solvent effect on growth" when a very simple correction for the molecular size between solute and solvent is implemented into the Monte Carlo scheme. The use of single point energy calculations (potential energy) displays limited sensitivity to the expected solvent effect in comparison to the use of distributions of MD derived values (binding free energy). Thus, the combination of relative binding free energy data and the proposed MC scheme is believed to be an effective path forward to providing insight into a solvent or additive effect on growth for more complex molecular systems that is simple to implement and does not come at a significantly high computational expense. In order to make an assessment of the data from simulation, plotting of the relative growth effect curvature is also introduced. [ABSTRACT FROM AUTHOR]

We have performed a comparison of the experimental thermal diffuse scattering (TDS) from crystalline Aspirin (form I) to that calculated from molecular dynamics (MD) simulations based on a variety of general force fields and a tailor-made force field (TMFF). A comparison is also made with Monte Carlo (MC) simulations which use a "harmonic network" approach to describe the intermolecular interactions. These comparisons were based on the hypothesis that TDS could be a useful experimental data in validation of such simulation parameter sets, especially when calculations of dynamical properties (e.g., thermodynamic free energies) from molecular crystals are concerned. Currently such a validation of force field parameters against experimental data is often limited to calculation of specific physical properties, e.g., absolute lattice energies usually at 0 K or heat capacity measurements. TDS harvested from in-house or synchrotron experiments comprises highly detailed structural information representative of the dynamical motions of the crystal lattice. Thus, TDS is a well-suited experimental data-driven means of cross validating theoretical approaches targeted at understanding dynamical properties of crystals. We found from the results of our investigation that the TMFF and COMPASS (from the commercial software "Materials Studio") parameter sets gave the best agreement with experiment. From our homologous MC simulation analysis we are able to show that force constants associated with the molecular torsion angles are likely to be a strong contributing factor for the apparent reason why these aforementioned force fields performed better.